It's in this context that a team of Swiss researchers has tested the effects of two weeks of twice-daily hand squeezing using a commercially available handgrip. The idea is that squeezing the grip for as long as possible gives students practice at self-control – it takes willpower to resist giving up as soon as squeezing becomes uncomfortable – and the experience teaches the idea that exerting effort isn't aversive.

The research published in Motivation Science showed that dozens of students who performed the two weeks of hand squeezing in their first semester achieved "considerably" higher grades seven months' later at the end of the academic year, as compared with a control group of dozens of other students who didn't do the squeezing.

The benefit of the training seemed to come from the fact that the hand-squeeze students changed their attitudes to studying – in the weeks before their exams they showed an increased willingness to put effort into their studies and they actually studied more. In contrast, simple lab tests showed their inhibitory control and resistance to fatigue were unaffected, leading the researchers to propose the training benefits occurred through "broader motivational self-regulatory mechanisms". It's unlikely that the benefits of the hand-squeezing were simply a placebo effect – there was no difference in the effects of the intervention whether the students were explicitly told that the idea was to boost their self-control or not.

"This result seems extraordinary" the researchers said. "Possibly, this repeated exertion of self-control [the hand-squeezing training] reshaped participants' perception of effortful tasks as aversive, making them more willing to exert effort." The finding adds to previous studies that have shown the benefits of self-control training in other contexts such as stopping smoking, and the power of other simple psychological interventions, such as self-affirmation exercises, to benefit students' academic performance.